Data From Dop To Pop

[iamjaideep80]

Hi guys........

I am facing a problem in DOPs . I want to get RBD data from DOPS to POPs.

I don't want Geometry Information, but just translation and rotation information of each object in RBD.

Plz tell me how can i do it in Houdini 8.

Thanking in advance.......

.............Jaideep

[mtucker]

There is currently no dedicated POP for doing this. But you can easily extract the information using DOP expression functions. To get the location of a DOP RBD object, use the expression:

dopoptions("/obj/dopnet1", "rbdobj1", "Position", "tx")

The last parameter then just has to be changed to ty, and tz to get all the position information which can be used easily with a Position POP.

The rotation information is a little bit more tricky. The Rotation POP requires you to specify the rotation as an axis and angle of rotation. But rotation information can only be extracted from DOPs as a quaternion (using "orientx/y/z/w" in place of tx in the above expression) or a set of Euler angles (using "rx/y/z"). Fortunately the conversion of a quaternion to an angle/axis value is pretty easy.

angle = acos(orientw) * 2

axis = normalize(orientx, orienty, orientz)

The other trick is making sure there is an easy expression to map your particles to the DOP object they represent. If there is a one to one correspondence between particles an DOP Objects, you can just use "$PT" in the above expression in place of "rbdobj1" to identify the DOP object of interest.

Mark

[iamjaideep80]

Hi Mtucker

Thanks for ur Reply.

I checked ur method, and it worked fine.......

Thank you very much.